The bill also calls for eliminating the diversity visa program, which offers the same number of visas to applicants in countries that are under-represented in the U.S. immigration system.

But what do we lose if that program goes away? Well, it depends on whom you ask. Below are some of the key points to consider when looking at this program.

Why was the program started?

The diversity visa actually grew out of an effort in the late 1980s to give more visas to European nations that were "adversely affected" when immigration laws were made more equitable in 1965.

The program was formally made into law with the Immigration Act of 1990, sponsored by the late Massachusetts Sen. Edward Kennedy. Before taking the shape of the lottery as we know it, the program had a built-in transition period from 1992-1994 where at least 40 percent of visas would go exclusively to Irish immigrants.

What's the scale of the diversity lottery?

There are 55,000 visas designated for the diversity lottery each year, but 5,000 of them usually go to another program for Central Americans. So the lottery typically awards 50,000 visas or less. To give this number some perspective, the U.S. issued roughly 1.1 million new green cards in 2011.

Who comes here on the diversity visa?

People from all over the world receive diversity visas, but the program especially benefits Africans and Eastern Europeans.

The criteria are looser for the diversity lottery than STEM. Applicants need a high school degree and work experience, among other qualifications, but advanced degrees aren't necessary. More importantly, diversity visa recipients don't need to be sponsored by a U.S. employer -- a major hurdle for visa applicants, even those with advanced degrees.

Why end it?

The main complaints are that the program is vulnerable to fraud and creates national security risks. Ironically, it's also been criticized for discriminating against certain groups of immigrants.

Diversity visas are only available to countries with low-rates of immigration to the U.S. For example, residents of Mexico, the Philippines, the Dominican Republic, India and China, among others, are ineligible. Countries in Africa and Eastern Europe are some of the main beneficiaries in recent years.

Are claims of fraud legit?

Among the eligible countries, the 50,000 visas are then distributed by lottery. The registration for the lottery is free and done over the Internet, which is where the worries about fraud arise.

The main victims of fraud are immigrants in sending countries, according to a 2007 report by the U.S. Government Accountability Office (GAO). In areas with limited access to the web, a third party acting as a "visa agent" will enter a person's name into the lottery, and then charge a fee to the person selected, the report says.

Is the diversity visa a threat to national security?

Critics of the program cite a few high-profile instances of terrorists gaining citizenship after a spouse or relative received a diversity visa. The most famous case is of an Egyptian terrorist who shot and killed two people in the Los Angeles International Airport in 2002. His wife had gotten a green card through the lottery.

Citizens of countries that are considered state sponsors of terrorism are also eligible for visas through the program. However, the 2007 GAO report says that it "found no documented evidence that DV immigrants from these, or other, countries posed a terrorist or other threat."

In addition, a 2011 report by the Congressional Research Service points out that those same countries are also eligible for green cards through other programs. In other words, people in countries like Iran, Syria and Sudan have other options for green cards aside from the lottery.

Immigrants across the board also undergo background checks to see if they are a national security risk, according to the 2011 report. So in that regard, the diversity lottery is essentially as vulnerable as any other visa program.

Where does each party stand?

Both sides agree on the need for more high-skilled visas. But there's a key difference between the bills: STEM would end the diversity visa program.

The White House has also voiced opposition, saying that the STEM bill is too narrow, and that Congress should focus on comprehensive immigration reform.

Should we keep the diversity visa?

The visas that STEM would add are important. Tech companies have been calling for more visas for years, and our immigration system should be able to adapt to the market. Software companies shouldn't need to open an office in the waters off the coast of California to get access to the workers they need. Judging by the proposed bills, both parties seem to agree on that.

But swapping those visas for the diversity lottery isn't an equal exchange. The diversity lottery represents a broader mix of immigrants -- since requirements are more basic, immigrants come from a variety of economic backgrounds, professions and countries of origin. Diversity visa holders might be lawyers, cab drivers or teachers. It's the luck of the draw.

In a country where 11 million people live without papers, cutting 50,000 more visas without improving legal immigration flows will do nothing to fix the greater system, according to Rachel Rosenbloom, an associate professor of law at Northeastern University School of Law.

"We have millions of people in this country who have been here for many years, working here, raising kids here, living in the shadows because of the inadequacy of our immigration system," she said. "We certainly need high-tech workers, but we also need farm workers, people who contribute to this country."

The diversity visa -- with its discriminatory history and happenstance method of allotment -- doesn't solve the problem of 11 million undocumented, but neither does STEM.

"There's been a recognition in Washington, probably for a decade, that we need comprehensive immigration reform and it's been stalled," Rosenbloom said. "It's been stalled by anti-immigrant sentiment, by partisan bickering."

If STEM is passed, it also means one less bargaining chip for a comprehensive immigration reform plan, hence the opposition from the White House. Lawmakers will have placated those lobbying for more high-skilled workers without addressing the nation's broader immigration needs.